Spark plug unit bushing



Dec. 11, 1945. "r. N. WILLCOX El'AL 2,390,820

SPARK PLUG UNIT BUSHING Filed Oct. 11, 1943 Inventors: Thomas N.Willcox, Hubert H.Race,

Their- Attorney.

Patented Dec. 11, 1945 UNITED STATES PATENT OFFIQE SPARK PLUG UNIT BUSHING 7 York Application October 11, 1943, Serial No. 505,730

12 Claims.

Our invention relates to bushings particularly adapted to provide a fluid seal about the connection of a spark plug unit to an ignition lead. Such a seal is very necessary to prevent sparkover of a spark plug terminal at high altitudes.

An object of our invention is to provide an improved bushing for a spark plug unit.

Another object of our invention is to provide an improved sealing bushing for a radio shielded ignition spark plug unit adapted to provide a good electrical contact between different elements of the radio shielding system. I

Further objects and advantages of our inven tion will become apparent and our invention will be better understood from the following description referring to the accompanying drawing, and

the features of novelty wich characterize our invention will be pointed out with particularity in the claims annexed to and forming part of this specification.

The drawing illustrates a bushing partly in section embodying our invention.

Referring to the drawing, we have shown an embodiment of our improved bushing for a radio shielded ignition spark plug unit which includes a relatively rigid tubular insulating terminal boot l formed of a suitable insulating material, such as a ceramic or boro-silicate mica and having an inwardly extending flange ll adjacent the lower end thereof. a In order to provide a fluid seal about a conductor adapted to be arranged in the bushing, a relatively resilient and yieldable insulating sleeve made of any suitable material, such as a heat and corona resistant synthetic rubber, is formed with a portion H which extends into the boot ID from the upper end thereof to the flange II and is intimately bonded to the inner surface of the boot in any suitable manner, as by molding it onto a roughened, cemented, or otherwise appropriately prepared surface, to provide a lining through substantially the full length of the boot. A collar I3 is formed on the resilient sleeve and extends over the upper edse of the boot III to provide a resilient cushion over the upper surface of the boot. and an upper tubular section It extends from the collar away from the boot and is formed of a thicker section than the portion of the sleeve l2 which extends into the boot to provide a substantially gas-tight seal of a spark an electrical connection between cooperating engaging surfaces of adjacent radio shielding elements for the ignition system. This bushing provides the desired rigid terminal boot together with a resilient and yieldable insulating sleeve bondedto the boot to insure against electrical discharges between the surfaces ofthe boot and the sleev from the terminal of an ignition conductor to ground and also provides for the desired good electrical contact between the cooperating radio shielding elements of an ignition system.

While we have illustrated and described particular embodiments of our invention, modifications thereof will occur to those skilled in the art. We desire it to be understood, therefore, that our invention is not to be limited to the particular arrangement disclosed, and we intend in the appended claims to cover all modifications which do not depart from the spirit and scope of our invention.

What we claim as new and desire to secure by Letters-Patent of the United States is:

1. A bushing for a spark plug unit including a rigid tubular insulating terminal boot, and a resilient insulating sleeve extending into said boot and intimately bonded to the inner surface thereof and having a collar extending over .the upper end of said boot.

2. A bushing for a spark plug unit including a relatively rigid tubular insulating terminal boot, and a relatively resilient insulating sleeve extending into said boot and bonded to the inner surface thereof having a collar extending over the upper end of said boot and an upper tubular section extending from said collar away from sai boot.

3. A bushing for a. spark plug unit including a rigid tubular insulating ceramic terminal boot,

and a resilient insulating sleeve extending into said boot and intimately bonded to the inner surface thereof having a collar and an upper tubular section extending from said collar away from said boot.

4. A bushing for a spark plug unit including a rigid tubular insulating boro-silicate-mica terminal boot. and a resilient insulating sleeve extending into said boot andintimately bonded to the relatively rigid tubular insulating terminal boot... and a relatively resilient insulating sleeve extending into said boot and bonded to the inner surface thereof for providing a lining through substantially the full length of said boot, said resilient sleeve having a collar and an upper tubular section extending from said collar away from said boot.

6. A bushing for a spark plug unit including a relatively rigid tubular insulating terminal boot having a roughened inner surface, and a relatively resilient insulating sleeve extending into said boot and bonded to said inner surface thereof having a collar extending over the upper end of said boot and an upper tubular section ex-- tending from said collar away from said boot.

'7. A bushing for a radio shielded spark plug including a rigid tubular insulating terminal boot,

a resilient insulating sleeve extending into said boot and bonded to the inner surface thereof having a collar and an upper tubular section extending from said collar away from said boot, and

an electrically conductive washer element bonded in said'collar and extending outwardly therefrom.

8. A bushing for a spark plug unit including a relatively rigid tubular insulating terminal boot, a relatively resilient insulating sleeve extending into said boot and bonded to the inner surface thereof having a collar extending over the upper end of said boot and an upper tubular section extending from said collar away from said boot, and an electrically conductive washer element bonded in said collar and extending outwardly therefrom.

9. A bushing for a spark plug unit including a relatively rigid tubular insulating terminal boot, a relatively resilient insulating sleeve extending into said boot and bonded to the inner surface thereof having a collar and an upper tubular section extending from said collar away from said boot, and an electrically conductive element having a central opening therethrough larger than the passageway through said resilient sleeve bonded in said collar and extending outwardly therefrom.

10. A bushing for a spark plug unit including a relatively rigid tubular insulating terminalboot, a relatively resilient insulating sleeve extending into said boot and bonded to the inner surface thereof for providing a lining through substantially the full length of said boot, said resilient sleeve having a collar and .an upper tubular section extending from saidcollar away from said boot, and an electrical conductive washer element bonded in said collar and extending outwardly therefrom. a

11. A bushing for a radio shielded ignition spark plug unit including a relatively rigid tubular insulating terminal boot, a relatively resilient insulating sleeve extending into said boot and bonded to the inner surface thereof having a collar extending over the upper end of said boot and an upper tubular section extending from said collar away from said boot, and an electrically conduotive element having a central opening therethrough larger than the passageway through said resilient sleeve bonded in said colla and extending outwardly therefrom.

12. A bushing for a radio shielded ignition spark plug unit including a. relatively rigid tubular insulating terminal boot,-a relatively resilient and yieldable insulating sleeve extending into said boot and bonded to the inner surface thereof for providing a lining through substantially the full length of said boot, said resilient sleeve having a collar extending over the upper end of said boot and outwardly therefrom and an upper tubular section extending from said collar away from said boot, and an electrically conductive washer element having a central opening therethrough larger than the passageway through said resilient sleeve bonded in said collar and extending outwardly therefrom.

THOMAS N. WILLCOX. HUBERT H. RACE. 

